SLM integration with Payment Gateway

Dear Gurus,

We are implementing SLM to avail prospective Supplier Registration, Pre-qualification and  performance Evaluation.

During prospective Supplier Registration, Suppliers need to pay pre-qualification fee before completing the registration.Only then our client will consider this supplier form evaluation and Approve/ Reject based on the pre-qualification criteria.We do not return the payment at any point. It will be treated as processing fee.

Please advise if anyone has implemented similar solution to capture the Pre-qualification fee. How do we achieve this ?

Thanks

Vinoth